Method for connecting two objects electrically

ABSTRACT

A groove, and a recess which communicates with the groove, are formed in a substrate. Next, a through hole which communicates with the groove is formed. Thereafter, a wire is formed on an upper surface of the substrate, and an individual electrode is arranged on a lower surface of the substrate. Further, a droplet of an electroconductive liquid is made to land on the recess, and the liquid is filled in the through hole via the groove. Next, the liquid filled in the groove, the recess, and the through hole is heated to harden. Further, the recess and the groove of the substrate are removed by cutting up to an area near the through hole. Accordingly, it is possible to connect electrically the connecting bodies arranged on both surfaces of the substrate by filling an electroconductive material in the through holes easily.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent ApplicationNo. 2007-084477 filed on Mar. 28, 2007, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for connecting objects such aswires and circuit elements which are arranged on both surfaces of asubstrate.

2. Description of the Related Art

A substrate which supplies an electric signal etc. to variousapparatuses, on which connecting objects (connecting bodies) such aswires and electrodes are arranged on both surfaces thereof, and theseconnecting objects are electrically connected via through holes formedin the substrate, is available.

As a method of connecting electrically the wires and electrodes whichare arranged on both surfaces of a substrate, a method of connecting theelectrodes and wires via through holes has been disclosed in FIG. 4 ofJapanese Patent Application Laid-open No. 2001-250842. In this method, asubstrate, in which through holes and wires are formed, is arrangedabove a semiconductor chip, on an upper surface of which electrodes areformed, such that the through holes are positioned on the electrodes,and an electroconductive material is filled in the through holes byjetting an electroconductive liquid directly in the through holes from anozzle of an ink-jet head, and the electrodes and the wires areconnected electrically via the through holes.

SUMMARY OF THE INVENTION

In a method of an electrical connection between both surfaces of asubstrate described in Japanese Patent Application Laid-open PublicationNo. 2001-250842, an electroconductive liquid which is jetted from anozzle of an ink-jet head is jetted onto the substrate so as to landdirectly in a through hole, and the electroconductive liquid is filledin the through hole. However, in recent years, a degree of integrationtends to be high for reasons such as making small a size of thesubstrate. As a result, a distance (gap) between through holes hasbecome very narrow. In this manner, when the through holes are arrangedat a narrow distance (gap), it is extremely difficult to fill the liquidaccurately in the through hole by jetting the liquid directly into thethrough hole from the nozzle, and there is a fear that the liquid mightadhere to the substrate without entering into the through hole. In sucha case, liquid filled in various holes might get shorted via the liquidadhered to the substrate. Moreover, filling the liquid accurately in thethrough hole by jetting the liquid directly on to the through hole froma nozzle of a high precision ink-jet head may be taken intoconsideration. However, such high precision ink-jet head being extremelyexpensive, the manufacturing cost would increase.

In view of this, an object of the present invention is to provide amethod of connecting objects which are arranged on both surfaces of asubstrate, by filling easily an electroconductive liquid in throughholes even when the through holes are arranged at a narrow distance(gap).

According to a first aspect of the present invention, there is provideda method for connecting two objects electrically by an electroconductiveliquid, including:

providing a substrate having a first surface and a second surface whichis opposite to the first surface;

forming a liquid-receiving portion, which receives the liquid, on thefirst surface of the substrate;

forming a channel of the liquid in the substrate which communicates withthe liquid-receiving portion;

forming a through hole in the substrate which communicates with thechannel and defines openings on the first and second surfaces,respectively;

arranging the two objects to interpose the substrate, at positions atwhich the two objects overlap with the openings of the through hole,respectively;

making a droplet of the liquid land on the liquid-receiving portion;

filling the liquid landed on the liquid-receiving portion to the throughhole via the channel;

bringing the liquid filled in the through hole in contact with theobjects arranged to interpose the substrate at positions at which thetwo objects overlap with the openings of the through hole, respectively;and

hardening the liquid filled in the through hole.

According to the first aspect of the present invention, theliquid-receiving portion is formed on the one surface of the substrate,and the channel communicating with the liquid-receiving portion isformed in the substrate, and further, the hole communicating with thechannel is formed in the substrate. Moreover, by making the droplet ofthe electroconductive liquid land on the liquid-receiving portion, thisliquid droplet for example is filled in the through hole via thechannel, by a capillary force. At this time, the liquid is filled in thethrough hole till the electroconductive liquid comes in contact with thetwo objects (connecting bodies) which are arranged on/above the openingsof the hole on both sides of the substrate. Consequently, by hardeningthe liquid filled in the through hole thereafter, the connecting bodiesarranged on/above both surfaces of the substrate are connectedelectrically via the electroconductive liquid filled in the throughhole. According to this method, even when the through holes are arrangedat a narrow distance, it is possible to connect electrically theconnecting bodies arranged on/above both surfaces of the substrate byfilling the electroconductive liquid in the through hole. Moreover, itis advantageous from a point of view of a manufacturing cost.

In the method for connecting two objects electrically according to thepresent invention, the liquid-receiving section may have a shape of arecess having a size which is capable of accommodating completely acircle having a diameter same as a diameter of the liquid droplet in aplan view; and a width of the channel may be smaller than the diameterof the liquid droplet. In this case, since the liquid-receiving portionhas a size which is capable of accommodating completely the circle inwhich a liquid droplet is projected, it becomes easy to make the liquiddroplet land on the liquid-receiving portion. Moreover, only by makingthe liquid droplet land on the liquid-receiving portion having a widearea, since the liquid flows by an effect of the capillary force forexample, in the channel having the width narrower than the diameter ofthe liquid droplet, and the liquid is filled in the through hole viathis channel, the filling of the electroconductive liquid in the throughhole is easy.

The method for connecting two objects electrically according to thepresent invention may further include removing a region of thesubstrate, which includes the liquid-receiving portion, after fillingthe liquid in the through hole and bringing the liquid droplet intocontact with the objects. Since the liquid-receiving portion and thechannel are only for letting the liquid flow to the through hole, whenthe liquid-receiving portion and the channel become unnecessary aftercompleting the filling, it is possible to remove the liquid-receivingportion and the channel. Accordingly, since it is possible to remove anunnecessary area of the substrate, it becomes possible to reduce a sizeof the substrate after making the electrical connections.

In the method for connecting two objects electrically according to thepresent invention, a plurality of individual channels which communicatewith the liquid-receiving portion may be formed as the channel uponforming the channel; a plurality of individual through holes whichcommunicate with the individual channels respectively may be formed asthe through hole, upon forming the through hole; the liquid landed onthe liquid-receiving portion may be filled in the individual throughholes via the individual channels respectively from the liquid-receivingportion, upon filling the liquid; and the individual channels may beelectrically isolated by removing the area of the substrate whichincludes the liquid-receiving portion, upon removing the area. In thiscase, since the plurality of (individual) holes are made to communicatewith one liquid-receiving portion via the plurality of (individual)channels, it is possible to fill the liquid in each of the through holesonly by making the liquid droplet land on one liquid-receiving portion.Thereafter, when the area of the substrate which includes theliquid-receiving portion is removed, it is possible to separate thechannels easily, and to make a state in which the through holes are notconnected electrically. In other words, for filling the liquid in theplurality of through holes, it is not necessary to change a position oflanding of the liquid droplet, and a filling job becomes easily.

In the method for connecting two objects electrically according to thepresent invention, a plurality of individual liquid-receiving portionsmay be formed as the liquid-receiving portion upon forming theliquid-receiving portion; and a plurality of individual channels whichcommunicate with the individual liquid-receiving portions respectivelymay be formed as the channel upon forming the channel; a plurality ofindividual through holes which communicate with the individual channelsmay be formed as the through hole upon forming the through hole; thedroplet of the liquid may be made to land on each of the individualliquid-receiving portions upon making the droplet of the liquid land onthe liquid-receiving portion; and the liquid landed on each of theindividual liquid-receiving portions may be filled in one of theindividual through holes via one of the individual channels upon fillingthe liquid. In this case, since it is possible to fill the liquid ineach of the through holes via the channels, by making the liquid land oneach of the individual liquid-receiving portions, the filling jobbecomes easy.

In the method for connecting two objects electrically according to thepresent invention, a distance between the individual liquid-receivingchannels may be greater than a distance between the individual throughholes. In this case, even when the distance between the individualthrough holes is narrow (short) and it is difficult to fill the liquiddirectly in each through hole, it is possible to fill the liquid in theplurality of individual through holes by making the liquid droplet landon each of the liquid-receiving portions.

In the method for connecting two objects electrically according to thepresent invention, a wiring which communicates with one of openings ofthe through hole may be formed as one of the objects, on the firstsurface of the substrate, at the time of arranging the objects.Accordingly, by filling the liquid in the through hole, it is possibleto connect one of the connecting bodies, which is arranged on onesurface of the substrate and the wire which is arranged on the othersurface of the substrate. Moreover, even when both the connecting bodiesare wirings, it is possible to connect the wires by filling the liquidin the through hole.

In the method for connecting two objects electrically according to thepresent invention, upon forming the through hole in the substrate, aprojection which projects inwardly from an inner wall of the throughhole may be also formed together with the through hole; and the wiringmay be formed such that the wiring covers a surface of the projectionupon arranging the objects. In this case, as the liquid is being filledin the through hole, a meniscus of the liquid rises from the opening ofthe through hole due to a surface tension, and when the liquid is filledfurther, the meniscus is destroyed at a front end of the projection, andthe liquid is spread around the opening of the through hole. At thistime, since the wiring is formed on the surface of the projection, theliquid upon the meniscus break at the projection is adhered assuredly tothe wiring, and it is possible to connect electrically with the wiring.

In the method for connecting two objects electrically according to thepresent invention, a liquid repellent property of a surface of the wiremay be lower than a liquid repellent property of a surface of thesubstrate, at an area different from another area at which the wiring isformed. In this case, the liquid which has overflowed from the throughhole is susceptible to be adhered to the surface of the wiring, insteadof flowing to the surface of the substrate.

In the method for connecting two objects electrically according to thepresent invention, the channel may be formed inside the substrate. Inthis case, since the channel is formed at the interior of the substratewhen the liquid droplet landed on the liquid-receiving portion flows tothe through hole via the channel, the liquid does not overflow outsidethe substrate from the channel.

In the method for connecting two objects electrically according to thepresent invention, the channel may be a groove formed on the firstsurfaces of the substrate. In this case, since the channel is a grooveformed on the surface on which the liquid-receiving portion is formed,it is possible to form the channel easily.

In the method for connecting two objects electrically according to thepresent invention, a liquid repellent property of the first surface ofthe substrate may be higher than a liquid repellent property of an innersurface of the liquid-receiving portion and a liquid repellent propertyof the groove. In this case, when the liquid flows from theliquid-receiving portion to the through hole via the groove, the liquidhardly overflows from the liquid-receiving portion and the groove.

The method of connecting electrically according to the presentinvention, may further include forming a liquid repellent film having aliquid repellent property higher than the liquid repellent property ofthe inner surface of the liquid-receiving portion and the liquidrepellent property of the groove, on the first surface of the substrate,before forming the channel. In this case, it is possible to preventassuredly the liquid from overflowing from the liquid-receiving portionand the groove.

In the method for connecting two objects electrically according to thepresent invention, the channel may be formed on the first surface of thesubstrate; and a liquid repellent property of the channel and a liquidrepellent property of the liquid-receiving portion may be lower than aliquid repellent property of an area on the first surface of thesubstrate, the area being different from another area at which theliquid-receiving portion and the channel are formed. In this case, theliquid droplet landed on the liquid-receiving portion, without flowingto the area having the high liquid repellent property, goes on wettingand spreading on the channel having the low liquid repellent property.

The method of connecting electrically according to the present inventionmay further include forming, on the first surface of the substrate, aliquid repellent film having a liquid repellent property higher than aliquid repellent property of an area at which the channel and theliquid-receiving portion are to be formed before forming the channel andthe liquid-receiving portion; and upon forming the channel and theliquid-receiving portion, the channel and the liquid-receiving portionmay be formed by partially removing the liquid repellent film. Forexample, after the liquid repellent film is formed by coating thesurface of the substrate by a fluorine film, by removing the coating onthe area which is to be the liquid-receiving portion and the channel, itis possible to form easily the liquid-receiving portion and the channelhaving the liquid repellent property inferior to the liquid repellentproperty of the area on which the liquid repellent film is formed. Theliquid repellent film may also be removed by irradiating a laser. Inthis case, a surface of the area from which the liquid repellent film isremoved becomes rough, and a liquid repellent property of a surface ofthis area is declined. Consequently, it is possible to form easily thearea having the low liquid repellent property.

In the method for connecting two objects electrically according to thepresent invention, one of the two objects may be arranged to be awayfrom the substrate upon arranging the two objects. In this case, whenthe liquid is being filled in the through hole, since the meniscus ofthe liquid rises from the opening of the through hole due to the surfacetension thereof, it is possible to bring the liquid in contact with theobjects (connecting body) by using the rising of the meniscus. Since itis possible to arrange the connecting body to be away from the surfaceof the substrate, a degree of freedom of arrangement of the connectingbodies becomes high.

According to the present invention, even when the through holes areformed at a narrow distance of arrangement, it is possible to fill theelectroconductive material easily in the through holes, and to connectelectrically the connecting bodies which are arranged on both surfacesof the substrate. Moreover, it is advantageous from the point of view ofthe manufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural view of an ink-jet printer;

FIG. 2 is a plan view of an ink-jet head excluding an FPC;

FIG. 3 is a plan view of the ink-jet head;

FIG. 4 is a partially enlarged view of FIG. 3;

FIG. 5 is a cross-sectional view taken along a line IV-IV in FIG. 4;

FIG. 6A to FIG. 6F are diagrams showing a process of connectingelectrically an electroconductive pattern and an individual electrode ofan embodiment in which FIG. 6A shows a channel forming step, FIG. 6Bshows a through hole forming step, FIG. 6C shows an arranging step, FIG.6D shows a liquid filling step, FIG. 6E shows a hardening (curing) step,and FIG. 6F shows a removing step;

FIGS. 7A and 7B are schematic diagrams of the channel forming step, thethrough hole forming step, the arranging step, and the liquid fillingstep, where, FIG. 7A is a plan view of a substrate and FIG. 7B is across-sectional view taken along a line VIIB-VIIB in FIG. 7A;

FIG. 8A and FIG. 8B are schematic diagrams of the removing step, where,FIG. 8A is a plan view of the substrate and FIG. 8B is a cross-sectionalview taken along a line VIIIB-VIIIB in FIG. 8A;

FIG. 9A and FIG. 9B are schematic diagrams corresponding to FIG. 7, of asecond modified embodiment, where, FIG. 9A is a plan view of thesubstrate and FIG. 9B is a cross-sectional view taken along a lineIXB-IXB in FIG. 9A;

FIG. 10A and FIG. 10B are schematic diagrams corresponding to FIG. 7, ofa third modified embodiment, where, FIG. 10A is a plan view of thesubstrate and FIG. 10B is a cross-sectional view taken along a lineXB-XB in FIG. 10A;

FIG. 11A and FIG. 11B are schematic diagrams corresponding to FIG. 7, ofa fourth modified embodiment, where, FIG. 11A is a plan view of thesubstrate and FIG. 11B is a cross-sectional view taken along a lineXIB-XIB in FIG. 11A;

FIG. 12A and FIG. 12B are schematic diagrams corresponding to FIG. 7, ofa fifth modified embodiment, where, FIG. 12A is a plan view of thesubstrate, and FIG. 12B is a cross-sectional view taken along a lineXIIB-XIIB in FIG. 12A;

FIG. 13A and FIG. 13B are schematic diagrams corresponding to FIG. 7, ofa sixth modified embodiment, where, FIG. 13A is a plan view of thesubstrate, and FIG. 13B is a cross-sectional view taken along a lineXIIIB-XIIIB in FIG. 13A;

FIG. 14A and FIG. 14B are schematic diagrams corresponding to FIG. 7, ofa seventh modified embodiment, where, FIG. 14A is a plan view of thesubstrate, and FIG. 14B is a cross-sectional view taken along a lineXIVB-XIVB in FIG. 14A;

FIG. 15A and FIG. 15B are schematic diagrams corresponding to FIG. 7, ofan eighth modified embodiment, where, FIG. 15A is a plan view of thesubstrate, and FIG. 15B is a cross-sectional view taken along a lineXVB-XVB in FIG. 15A.; and

FIG. 16A and FIG. 16B are schematic diagrams corresponding to FIG. 7, ofa fourteenth modified embodiment, where, FIG. 16A is a plan view of thesubstrate, and FIG. 16B is a cross-sectional view taken along a lineXVB-XVB in FIG. 16A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be described below. Thisembodiment is an example in which the present invention is applied to apiezoelectric actuator of an ink-jet printer which records a desiredimage and characters by jetting the ink on to a recording paper, thepiezoelectric actuator applying a jetting pressure to an ink.

Firstly, the ink-jet printer will be described. As shown in FIG. 1, anink-jet printer 100 includes a carriage 2 which is movable in a left andright direction in FIG. 1, an ink-jet head 1 of a serial type which isprovided in the carriage 2 and which jets the ink onto a recording paperP, and transporting rollers 3 which transport the recording paper P in afrontward direction in FIG. 1. The ink-jet head 1 moves in the left andright direction (scanning direction) integrally with the carriage 2, andjets the ink onto the recording paper P from nozzles 20 (refer to FIG.2) to record desired characters and image, the nozzles being arranged ina lower surface of the ink-jet head 1. Moreover, the recording paper Pwith an image recorded thereon is discharged frontward (paper feedingdirection) by the transporting rollers 3.

Next, the ink-jet head 1 will be described below. As shown in FIGS. 2 to5, the ink-jet head 1 includes a channel unit 4, a piezoelectricactuator 5, and a Flexible Printed Circuit (FPC) 40.

Firstly, the channel unit 4 will be described below. As shown in FIG. 5,the channel unit 4 includes a cavity plate 10, a base plate 11, amanifold plate 12, and a nozzle plate 13 which are joined in stackedlayers in this order from an upper layer.

As shown in FIGS. 2 to 5, a plurality of pressure chambers 14 arrangedalong a plane are formed as holes formed through the cavity plate 10which is at a topmost position (uppermost layer) in the four plates 10to 13. An upper side and a lower side of the pressure chambers 14 iscovered by the base plate 11 and a vibration plate 30 which will bedescribed later. Moreover, the pressure chambers 14 are arranged in tworows and in each of the rows, a plurality of pressure chambers 14 arealigned in a paper feeding direction (vertical direction in FIG. 2).Furthermore, each of the pressure chambers 14 has a substantiallyelliptical shape in a plan view which is elongated in the scanningdirection (left and right direction).

As shown in FIGS. 4 and 5, communicating holes 15 and 16 are formed inthe base plate 11, at positions overlapping with both end portions ofthe pressure chamber 14 in a plan view. Moreover, two manifolds 17extended in the paper feeding direction are formed in the manifold plate12, such that the manifolds 17 overlap with a portion toward thecommunicating hole 15 of the pressure chambers 14 arranged in two rows.These two manifolds 17 communicate with an ink supply port 18 formed inthe vibration plate 30 (refer to FIG. 2) which will be described later,and the ink is supplied to the manifolds 17 from an ink tank which isnot shown in the diagram, via the ink supply port 18. Furthermore, aplurality of communicating holes 19 which communicate with thecommunicating holes 16 are formed in the manifold plate 12 at positionsoverlapping with an end portion of the pressure chambers 14, the endportion being opposite to the manifolds 17 in a plan view.

A plurality of nozzles 20 is formed in the nozzle plate 13 at positionsoverlapping with the communicating holes 19 in a plan view. As shown inFIG. 2, the nozzles 20 are arranged in two nozzle rows. In each of thenozzle rows, nozzles 20 are aligned in the paper feeding direction so asto overlap with the end portion of the pressure chambers 14 arranged intwo rows along the paper feeding direction, the end portion beingopposite to the manifolds 17.

As shown in FIG. 5, the manifold 17 communicates with the pressurechamber 14 via the communicating hole 15, and further, the pressurechambers 14 communicate with the nozzles 20 via the communicating holes16 and 19, respectively.

Next, the piezoelectric actuator 5 will be described below. As shown inFIGS. 2 to 5, the piezoelectric actuator 5 includes the vibration plate30 which is arranged on an upper surface of the cavity plate 10 havingthe pressure chambers 14, a piezoelectric layer 31 which is formed, onan upper surface of the vibration plate 30, to be spread continuouslyover the pressure chambers 14, and a plurality of individual electrodes32 arranged on an upper surface of the piezoelectric layer 31.

The vibration plate 30 is a metallic plate having a substantiallyrectangular shape in a plan view. The vibration plate 30 is joined tothe upper surface of the cavity plate 10 at a portion surrounding thepressure chambers 14, in a state in which the vibration plate 30 coversthe pressure chambers 14. Moreover, the piezoelectric layer 31 isarranged between the individual electrodes 32 and the upper surface ofthe vibration plate 30 which is electroconductive, and the upper surfaceof the vibration plate 30 also serves as a common electrode whichgenerates an electric field in a thickness direction of thepiezoelectric layer 31.

The piezoelectric layer 31 is formed on the upper surface of thevibration plate 30 in a plan view. The piezoelectric layer 31 is made ofa piezoelectric material, which is composed mainly of lead zirconatetitanate (PZT) which is a solid solution of lead titanate and leadzirconate, and which is a ferroelectric substance. This piezoelectriclayer 31 is formed continuously to cover the pressure chambers 14.

The individual electrodes 32 having a substantially elliptical shapeslightly smaller than the pressure chambers 14 are formed on the uppersurface of the piezoelectric layer 31, corresponding to the pressurechambers 14 respectively. These individual electrodes 32 are formed inan area facing the corresponding pressure chambers 14, at a centralportion away from a periphery of the pressure chambers 14. Theindividual electrodes 32 are formed of an electroconductive materialsuch as gold, silver, palladium, platinum, or titanium. Further, theindividual electrodes 32 are arranged in two rows, and one of endportions near the communicating hole 15 (left or right end portions) ofthe individual electrodes 32 are extended to an outer area of thepiezoelectric layer crossing over the periphery of the pressure chamber14, the outer area overlapping with an outer side of the pressurechamber 14.

Next, the FPC 40 which transmits the drive voltage supplied from adriver IC (not shown) to the individual electrodes 32 will be describedbelow. As shown in FIGS. 3 to 5, the FPC 40 has a substrate 41 which isarranged on an upper surface of the piezoelectric actuator 5. Thesubstrate 4 is made of a synthetic resin material such as a polyimideresin.

A plurality of wires 42 is formed on an upper surface of the substrate41. Moreover, a plurality of recesses 47 ((individual) liquid-receivingportions) and a plurality of grooves ((individual) channels) 46 in whichan electroconductive material 43 is filled are formed on the uppersurface of the substrate 41. Furthermore, a plurality of through holes(individual through holes) 48 which make communicate the upper surfaceand a lower surface of the substrate 41, is formed in the substrate 41,and the electroconductive material 43 is filled in these through holes48. As shown in FIG. 5, the electroconductive material 43 which isexposed from a lower side of the through hole 48 (lower surface of thesubstrate 41) is bulged downward in a form of a projection, and isconnected to the individual electrode 32 by making a contact with theindividual electrode 32.

One end of each of the wires 42 is connected to a part of a periphery ofthe respective through hole 48, and is connected electrically by makinga contact with the electroconductive material 43 filled in the throughhole 48. The other end of each of the wires 42 is connected electricallyby making a contact with a terminal of the drive IC which is not shownin the diagram. Accordingly, a predetermined drive voltage is applied tothe individual electrodes 32 from the terminals of the driver IC via thewires 42 and the electroconductive material 43, at the time of drivingthe piezoelectric actuator 5. When the predetermined drive voltage isapplied to the individual electrode 32, droplets of ink are jetted fromthe nozzle 20 corresponding to this individual electrode 32.

Next, in the ink-jet head 1 described above, a method for connectingelectrically the wires 42 formed on an upper surface of the FPC 40 andthe individual electrodes 32 of the piezoelectric actuator 5 arranged ona lower surface side of the FPC 40, will be described below withreference to FIGS. 6A to 8B.

Firstly, as shown in FIG. 6A, the substrate 41 made of a flexiblesynthetic resin material such as a polyimide resin, an aramid resin, aphenolic resin, and a liquid crystal polymer is provided. A filledchannel (filling channel) 49 having the recesses 47, and the grooves 46communicating with the recesses 47 respectively are formed on the uppersurface (first surface) of the substrate 41 (filling channel formingstep). As shown in FIG. 7A, the recesses 47 have a circular shape in aplan view, and are arranged in a staggered (zigzag) form along avertical direction in FIG. 7A. One end of the grooves 46 communicateswith the recess 47, and the groove 46 is extended in a left and rightdirection in FIG. 7A. Moreover, a cross-section of the groove 46 has asubstantially rectangular shape.

Here, the recess 47 is formed such that a diameter of the recess 47 islarger than a width of the groove 46. The recesses 47 and the grooves 46are formed by a laser machining in which a laser such as an excimerlaser, a YAG laser, or a femto second laser is used. At this time, aliquid repellent property of an inner surface of the groove 46 and therecess 47 is inferior to a liquid repellent property of the uppersurface of the substrate 41. Since a surface irradiated by the laserbecome a rough surface, a liquid repellent property of a surface whichdefines the recesses 47 and the grooves 46 becomes inferior. In thismanner, the laser machining is preferable for realizing easily the innersurface of the recess 47 and the groove 46 having the liquid repellentproperty inferior to the liquid repellent property of the upper surfaceof the substrate 41.

Next, as shown in FIG. 6B, the through hole 48 cut through the uppersurface and the lower surface of the substrate 41 is formed at one endof the groove 46, where the recess 47 is not formed (through holeforming step). In other words, the recess 47 and the through hole 48communicate via the groove 46. The through hole 48 is formed by lasermachining in which a laser such as the excimer laser, the YAG laser, orthe femto second laser is used. At this time, as shown in FIG. 7, adistance L1 between the recesses 47 is made to be longer than a distanceL2 between the through holes 48.

Next, as shown in FIG. 6C, the wire 42 is formed on the upper surface ofthe substrate 41 by a method such as a screen printing, a vapordeposition method, and a sputtering method, such that one end thereof isconnected to a part of a periphery of the through hole 48. A liquidrepellent property of a surface of the wire 42 is inferior to the liquidrepellent property of the surface of the substrate 41. The other end ofthe wire 42 is connected to the terminal of the driver IC (not shown).Moreover, the substrate 41 is arranged above the upper surface of theindividual electrode 32 which is arranged on the piezoelectric actuator5, such that an opening of the through hole 48 is positioned at apredetermined distance (arranging step). Accordingly, the individualelectrode 32 and the wire 42, which are connecting bodies, are arrangedon/above both surfaces (respective surfaces) of the substrate 41,respectively. The connecting bodies such as the individual electrode 32and wire 42 may be arranged so as to partially overlap with the openingsof the through hole 48.

Next, as shown in FIG. 6D, an electroconductive liquid droplet 51 isjetted, by a liquid-droplet jetting apparatus 50 such as an ink-jet headand a micro dispenser, to land on the recess 47 communicating with eachgroove 46, and an electroconductive liquid 52 is filled into the throughhole 48 via the groove 46. It is possible to use various liquids as theelectroconductive liquid 52. An example of a case in which a nanoelectroconductive particle ink in which metallic nano particles (ofabout 7 nm diameter for example) of a metal such as silver and goldexist in independently dispersed state without being coagulated(agglutinated) in a solvent, is discussed below.

As shown in FIGS. 6D, 7A and 7B, when the liquid droplet 51 lands on therecess 47, since the width of the groove 46 is sufficiently narrow, theliquid 52 is sucked into the groove 46 due to an effect of a capillaryforce. Since the inner surface of the groove 46 is susceptible towetting (wetting angle is smaller than 90 degree), the liquid 52 goes onspreading and wetting along the groove 46 (capillary phenomenon). Due tothe capillary phenomenon, the liquid 52 which is flowed into the groove46 flows up to the through hole 48. At this time, the liquid 52 iscompletely filled in the through hole 48, and makes a contact with thewire 42, and then by further filling the liquid 52, the surface of theliquid 52 at a lower end opening of the through hole 48 is bulged toform a projection because of the surface tension, and a portion which isprojected makes a contact with the individual electrode 32 (liquidfilling step).

Here, as it has been described above, since the liquid repellentproperty of the upper surface of the substrate 41 is superior to theliquid repellent property of the inner surface of the groove 46 and therecess 47, the liquid 52 flowing from the recess 47 to the groove 46hardly overflows to the upper surface of the substrate 41.

As shown in FIGS. 7A and 7B, it is preferable to form the groove 46 andthe recess 47 at the channel forming step described above, such that thediameter of the recess 47 (70 μm for example) is larger than a diameterof the liquid droplet 51 (40 μm for example) during flight beforelanding, and further, the width of the groove 46 (20 μm for example) issmaller than the diameter of the liquid droplet 51. In this case, sincethe recess 47 has a size which is capable of including (accommodating)completely a circle projected by the liquid droplet 51, it becomes easyto make the liquid droplet 51 land on the recess 47. Moreover, only bymaking the liquid droplet 51 land in the recess 47 having a wide area,the liquid 52 flows to the groove 46 having the width narrower than thediameter of the liquid droplet 51 due to the effect of the capillaryforce, and the liquid is filled in the through hole 48 via this groove46. Therefore, the filling of the liquid 52 in the through hole 48 iseasy.

Moreover, when the distance between the recesses 47 is narrow, it mightbe difficult to fill the liquid 52 by directly jetting into the throughhole 48. Even in such a case, in the present invention, since thedistance between the recesses 47 communicating with the through holes 48is longer than the distance between the through holes 48, it is possibleto fill the liquid 52 in the through holes 48 by making a liquid dropletland on each of the recesses 47.

Furthermore, since the liquid repellent property of the surface of thewire 42 is lower than that of the surface of the substrate 41, theliquid 52 overflowed from the through hole 48 is not flowed to thesurface of the substrate 41, and is easily adhered to the surface of thewire 42 having the liquid repellent property lower (wetting anglesmaller) than the liquid repellent property of the surface of thesubstrate 41.

Next, as shown in FIG. 6E, the substrate 41 is heated to a predeterminedtemperature (for example, about 200° C. when the substrate 41 is made ofa polyimide resin) which is not higher than an upper temperature limitof the substrate 41, and the liquid 52 filled in the grooves 46, therecesses 47, and the through holes 48 is hardened (cured) by baking(hardening step, curing step). In other words, the liquid 52 becomes theelectroconductive material 43 upon hardening. Since the individualelectrode 32 and the wire 42 arranged on two surfaces of the substrate41 make contact with this electroconductive material 43, the individualelectrode 32 and the wire 42 are connected electrically via theelectroconductive material 43.

Further, as shown in FIGS. 6F, 8A and 8B, the recess 47 and the groove46 of the substrate 41 are removed by cutting by a dicer etc., in anarea near the through hole 48 (removing step). Accordingly, when therecess 47 and the groove 46 are not removed, dust may be adhered betweenthe recesses 47 and the grooves 46, and it may cause a short-circuit.Therefore it is possible to prevent from getting shorted (short-circuit)by removing the recess 47 and the groove 46 of the substrate 41.

In the above discussion, an ink having nano electroconductive particlesis exemplified as the electroconductive liquid 52. However, it is alsopossible to use other electroconductive liquids such as a fused (melted)solder. For example, in a case of using the solder, at the liquidfilling step (FIG. 6D), the solder is filled in the groove 46, therecess 47, and the through hole 48 with the substrate 41 heated to atemperature of a fusing (melting) point or more of the solder (100° C.to 180° C. for example). Then, at the hardening step (FIG. 6E), it ispossible to harden the solder filled in the groove 46, the recess 47,and the through hole 48 by lowering the temperature of the substrate 41to a temperature lower than the melting point of the solder.

Moreover, in the above example, the removing step (FIG. 6F), in whichthe recess 47 and the groove 46 of the substrate are removed by cuttingby a dicer up to an area near the through hole 48, is carried out afterthe hardening step (FIG. 6E). However, it is also possible to carry outthe removing step before the hardening step, in other words, it ispossible to carry out the removing step immediately after the liquidfilling step (FIG. 6D). It is possible to use this in a case in whichthe liquid 52 does not flow from a cutting location due to a reason suchas a high viscosity of the liquid 52 filled in the through hole 48. Inother words, even in a state before hardening the liquid 52, when it ispossible to maintain the state of the liquid 52 filled in the throughhole 48 having made a contact with the wire 42 and the individualelectrode 32, the removing step may be carried out before the hardeningstep.

According to a method for making an electrical connection between thewire formed on the FPC 40 and the individual electrode 32 arranged inthe piezoelectric actuator 5 (a method of connecting electrically(method for making electrical connections between both surfaces ofsubstrate), as described above, the following effect is achieved. Therecess 47, and the groove 46 which communicates with the recess 47, areformed on one surface of the FPC 40, and further, the through hole 48which communicates with the groove 46 is formed in the FPC 40. When theliquid droplet 51 lands on the recess 47, this liquid droplet 51advances via the groove 46 by the capillary force and reaches thethrough hole 48 to fill the through hole 48. Furthermore, the liquid 52is filled in the through hole 48 till the electroconductive liquid 52makes a contact with each of the wire 42 and the individual electrode32, the wire 42 being connected to a part of the surrounding portion ofthe through hole 48 on the upper surface (first surface) of the FPC 40,and the individual electrode 32 being arranged near an opening of thethrough hole 48 on the lower surface (second surface) of the FPC 40.Hereafter, when the liquid 52 in the through hole 48 is hardened, thewire 42 and the individual electrode 32 on both surfaces of the FPC 40are connected electrically via the electroconductive liquid 43 filled inthe through hole 48. According to this method, even in a case in whichthe through holes 48 are formed at a narrow distance, it is possible tofill the electroconductive material 43 in the through holes 48, and toconnect electrically the wire 42 and terminals of the driver IC arrangedon both surfaces of a substrate such as the FPC 40. Moreover, this isadvantageous from a point of view of a manufacturing cost.

Next, modified embodiments in which various modifications are made inthe embodiment will be described below. However, same reference numeralsare used for components having a structure similar to the components inthe embodiment, and the description of such components is omitted.

First Modified Embodiment

In the embodiment described above, the recess 47 and the groove 46 ofthe substrate 41 has been removed by cutting by a dicer etc., up to thearea surrounding the through hole 48. However, in a case of using thisrecess 47 and the groove 46 as terminals and wires, the removing stepmay not be carried out. In other words, the recess 47 and the groove 46may not be removed.

Second Modified Embodiment

In the embodiment described above, the plurality of grooves 46 has beenformed in the substrate 41, and a recess 47 has been formed at one endof each groove 46. However, the number and an arrangement of the grooves46 and the recesses 47 may be arbitrary. For example, as shown in FIG.9, one recess 47, one groove 46, a plurality of branched grooves 146,and a plurality of through holes 48 are formed in the substrate 41. Oneend of the groove 46 communicates with the recess 47, and the other endof the groove 46 communicates with one through hole 48. Moreover, oneend of the branched grooves 146 communicates with a middle portion ofthe groove 46 in a longitudinal direction, and the other end of thesebranched grooves 146 communicates with the respective through hole 48.Accordingly, when the liquid droplet 51 jetted from the liquid-dropletjetting apparatus 50 lands on the recess 47, the liquid 52 is suckedinto the groove 46 by the effect of the capillary force. Moreover, theliquid 52 which flows through the groove 46 is further sucked into thebranched groove 146 due to the capillary force. In this manner, theliquid 52 flowing through the groove 46 and the branched groove 146 isfilled in each through hole 48. Furthermore, the liquid 52 filled in thethrough hole 48 makes a contact with the wire 42 which is formed on theupper surface of the substrate 41 and the individual electrode 32 whichis arranged on the lower surface of the substrate 41. Thereafter, theliquid 52 is hardened during the hardening step. Further, during theremoving step, the recess 47, the groove 46, and the branched grooves146 of the substrate 41 are removed by cutting up to an area near thethrough hole 48 (to an extent that the groove 46 and the branchedgrooves 146 do not communicate). Accordingly, it is possible to separate(divide) electrically the liquid 52 in the through holes 48 which hadbeen electrically connected because of the electrical connection amongthe recess 47, the groove 46, the branched grooves 146, and the throughhole 48.

In case the recess 47, the groove 46, and the branched grooves 146 areremoved during the removing step, it is possible to fill the liquid 52in the plurality of through holes 48 by making the plurality of throughholes 48 communicate with one recess 47 via the groove 46 and thebranched groove 146, and by making land the liquid droplet 51 on onerecess 47. Moreover, the recess 47, the groove 46, and the branchedgroove 146 are removed up to the area near the through hole 48 (to anextent that the groove 46 and the branched groove 146 do notcommunicate) to divide the groove 46 and the branched groove 146, andthe liquid 52 in the through holes 48 are disconnected electrically.Since it is not necessary to change a position of landing of the liquiddroplet 51 for filling the liquid 52 in each through hole 48, a fillingjob becomes easy.

Third Modified Embodiment

As described in the embodiment, the terminal of the driver IC and theindividual electrode 32 may be connected electrically by electricallyconnecting the electroconductive material 43 to the terminal of thedriver IC via the wire 42 formed on the upper surface of the substrate41. As shown in FIG. 10A and FIG. 10B, a terminal 61 of a driver IC 60is arranged on the upper surface of the substrate 41, at a position ofan opening of the through hole 48. Here, by bringing a portion which isformed as a projection upward due to bulging due to the surface tensionof the liquid 52 filled in the through hole 48, in contact with theterminal 61 of the driver IC 60, it is possible to connect electricallythe terminal 61 of the driver IC 60 and the individual electrode 32arranged on both surfaces of the substrate 41. In other words, it ispossible to connect the terminal 61 of the driver IC arranged on theupper surface of the substrate 41 and the individual electrode 32arranged on the lower surface of the substrate 41, without connecting bya wire. In this manner, by filling the liquid 52 in the through hole 48,it is possible to connect the terminal 61 of the driver IC arranged onthe upper surface of the substrate 41 and the individual electrode 32arranged on the lower surface of the substrate 41.

Fourth Modified Embodiment

In the embodiment described above, the individual electrode 32 arrangedon the lower surface of the substrate 41 and the wire 42 formed on theupper surface of the substrate 41 have been electrically connected viathe liquid 52 filled in the through hole. However, instead of theindividual electrode 32, a wire 142 may be formed on the lower surfaceof the substrate 41 as shown in FIG. 11. In this case, it is possible toconnect the wire 142 formed on the lower surface of the substrate 41 andthe wire 42 formed on the upper surface of the substrate 41 via theliquid 52 filled in the through hole 48 by connecting the wire 142 to apart of the periphery of the through hole 48.

Fifth Modified Embodiment

As shown in FIG. 12, a liquid repellent film 45 which is made of afluororesin and which improves a liquid repellent property of the uppersurface of the substrate 41, may be formed on the upper surface of thesubstrate 41. It is possible to carry out a step of forming this liquidrepellent film 45 (liquid repellent film forming step) before thechannel forming step. It is possible to form this liquid repellent film45 by a method such as a spin coating method. Moreover, a notch 41 a atwhich the surface of the substrate 41 is exposed is to be formed (may beformed) by removing the liquid repellent film 45 only near an endportion of a portion at which the through hole 48 and the wire 42 areconnected. It is possible to form this notch 41 a by removing the liquidrepellent film 45 by irradiating a laser with a weak power. In thismanner, with the liquid repellent film 45 formed on the substrate 41,there is a marked improvement in the liquid repellent property on theupper surface of the substrate 41 as compared to a state without theliquid repellent film 45, and it is possible to prevent assuredly theliquid 52 overflowing from the recess 47 and the groove 46. Further, asthe liquid 52 is filled gradually in the through hole 48, the meniscusof the liquid rises from the opening of the through hole 48 due to thesurface tension, and when the liquid 52 is filled further, the meniscusis destroyed and the liquid 52 is spread around the opening of thethrough hole 48. At this time, since the liquid repellent film 45 is notformed at the notch 41 a of the substrate 41, the liquid repellentproperty at that portion is declined. Accordingly, the liquid 52 havingthe meniscus destroyed becomes susceptible to flow toward the wire 42,and to be adhered to an electroconductive pattern 132. In other words,it is possible to connect electrically the liquid 52 and the wire 42assuredly.

Sixth Modified Embodiment

In the embodiment described above, the liquid 52 has been filled fromthe recess 47 to the through hole 48 via the groove 46 formed in thesurface of the substrate 41. However, as shown in FIG. 13, an internalchannel 70 which makes communicate an inner portion of the substrate 41up to the through hole 48 from the recess 47 may be formed in asubstrate 141, and the liquid may be filled in the through hole 48 fromthe recess 47 via this internal channel 70. In this case, the internalchannel 70 is formed by forming a lower member 141 a in which the recess47, the through hole 48, and the groove are formed, and then arrangingan upper member 141 b to cover the groove. Accordingly, when the liquiddroplet 51 landed on the recess 47 flows to the through hole 48 via theinternal channel 70, the liquid droplet 51 does not overflow outside thesubstrate 41.

Seventh Modified Embodiment

As shown in FIG. 14, a projection 148 a projecting toward the center ofthe through hole 148 may be formed in the circumference portion of thesubstrate which defines the through hole and which has circular shape,and a wire 242 may be formed to cover a surface of the projection 148 a.Accordingly, as the liquid 52 is filled gradually in a through hole 148,due to the surface tension thereof, a meniscus rises from an opening ofthe through hole 148, and when the liquid is filled further, themeniscus is destroyed at a front end of the projection 148 a, and theliquid 52 is spread around the opening of the through hole 148. At thistime, since the wire 242 is formed on a surface of the projection 148 a,the liquid 52 having the meniscus destroyed at the projection 148 a isadhered assuredly to the wire 242, and it is possible to connectelectrically with the wire 242.

Eighth Modified Embodiment

In the embodiment described above, the plurality of grooves 46 has beenformed in the substrate 41, and the recess 47 communicates one end ofeach groove 46, and the electroconductive liquid 51 which is jetted fromthe liquid-droplet jetting apparatus 50 has been made to land on therecess 47. However, a location at which the liquid droplet 51 is to bemade to land need not be the recess, and it may be another structureprovided that it is possible to suppress wetting and spreading of theliquid droplet 51 that has landed, and to guide the liquid droplet tothe groove 46. For example, as shown in FIG. 15, instead of the recess47, there may be an area 147 which is on a same plane as a surroundingarea of the area 147, and which is more susceptible to wetting ascompared to the surrounding area, and the area 147 may be connected tothe groove 46 via an inclined surface 148 which is susceptible towetting similarly as the area 147. Accordingly, the liquid droplet 51which has landed on the area 147 of the substrate 41 is not spreadwetting the surrounding, and is sucked to the groove 46 via the inclinedsurface 148.

Ninth Modified Embodiment

The recess 47 need not necessarily have a circular shape in a plan view,and may be formed to have an arbitrary shape such as a rectangularshape, an elliptical shape, and a polygonal shape, provided that it ispossible to secure an area which makes the liquid droplet 51 landassuredly.

Tenth Modified Embodiment

A cross-sectional shape of the groove 46 need not be necessarily asubstantially rectangular shape, and it may be an arbitrary shape suchas a semicircular shape and a triangular shape. Moreover, the width ofthe groove 46 may not be uniform, and a part of the groove may be formedto have more width (formed to be wider) for example.

Eleventh Modified Embodiment

In the embodiment described above, the recess 47 has been formed to havea diameter larger than the diameter of the liquid droplet 51 such thatthe liquid 52 filled in through holes 48 does not get shorted via theliquid 52 which is adhered to the surface of the substrate 41 withoutbeing landed on the recess 47. However, when the liquid 52 filled in thethrough holes 48 does not get shorted, or when the recess 47 is removedin the removing step, the recess 47 may be formed such that the diameterof the recess 47 is larger than the diameter of the liquid droplet 51.

Twelfth Modified Embodiment

Connecting objects such as wires and driver IC need not be necessarilyarranged (arranging step) after forming the filling channel (fillingchannel forming step) and forming the through hole (through hole formingstep), and an order of steps may be arbitrary. With the connectingobjects arranged, the filling channel and the through hole may beformed, or the filling channel and the through hole may be formed beforethe liquid filling step, and then the connecting objects may bearranged.

Thirteenth Modified Embodiment

The embodiment is applicable not only to a case of connectingelectrically the connecting objects which are arranged on/above bothsurfaces of the FPC 40 provided in the ink-jet printer 100, but also toa case of connecting electrically the connecting objects which arearranged on/above both surfaces of a substrate. In this case, thesubstrate is not restricted to be made of a flexible resin material suchas the FPC 40, and may be made of a highly rigid ceramics material suchas alumina and zirconia, or an insulating material(non-electroconductive material) such as a glass material.

Fourteenth Modified Embodiment

The filling channel may not necessarily have a recess and/or a groove.For example, a substrate 600 shown in FIG. 16 has a high liquidrepellent property area 601 and a low liquid repellent property area 602which is surrounded by the high liquid repellent property area 602, andthe low liquid repellent property area 601 functions as the fillingchannel. Concretely, the low liquid repellent property area 602 has aplurality of liquid-receiving portions 602 a having a substantiallycircular shape in a plan view, and a plurality of extending portions 602b each extending from the liquid-receiving portion 602 a toward thethrough hole 48. An area around the liquid-receiving portion 602 a andthe extending portion 602 b is surrounded by the high liquid repellentproperty area 601, or in other words, the liquid-receiving portion 602 aand the extending portion 602 b are defined by the high liquid repellentproperty area 601. Here, when a liquid droplet of the liquid 52 is madeto land on the liquid-receiving portion 602 a, the liquid 52 flows tothe through hole 48 via the extending portion 602 b having the lowliquid repellent property. In this manner, the filling channel is notrestricted to a groove etc. which guides the liquid to the through holeby using the capillary force. It is possible to form an area having aliquid repellent property remarkably lower than a liquid repellentproperty of a surrounding area, and to use this low liquid repellentproperty area as the filling channel. Here, by coating an entire surfaceof the substrate 600 by a material having a high liquid repellentproperty, such as a fluororesin, and thereafter, by irradiating a laseron the area to be the liquid-receiving portion 602 a and the extendedportion 602 b, it is possible to form easily the high liquid repellentproperty area 601 and the low liquid repellent property area 602 b.Since it is possible to remove the coating of the fluororesin and tomake rough the surface of the substrate 600 by irradiating the laser, itis possible to form easily the low liquid repellent property area 602.

1. A method for connecting two objects electrically by anelectroconductive liquid, comprising: providing a substrate having afirst surface and a second surface which is opposite to the firstsurface; forming a channel of the liquid in the substrate, on the firstsurface of the substrate; forming a through hole in the substrate whichcommunicates with the channel and defines openings on the first andsecond surfaces, respectively; arranging the two objects to interposethe substrate, at positions at which the two objects overlap with theopenings of the through hole, respectively; filling the liquid to thethrough hole via the channel, by a capillary force or a surface tensionbetween the liquid and a channel-defining surface; bringing the liquidfilled in the through hole in contact with the objects arranged tointerpose the substrate at positions at which the two objects overlapwith the openings of the through hole, respectively; and hardening theliquid filled in the through hole, wherein, when bringing the liquidfilled in the through hole in contact with the objects, the liquid issupplied into the through hole, so that a surface of the liquid at anend opening of the through hole bulges to form a projection due tosurface tension, and the projection of the surface of the liquid makescontact with one of the objects.
 2. The method for connecting twoobjects electrically according to claim 1, further comprising removing aregion of the substrate, which includes a part of the channel, afterfilling the liquid in the through hole and bringing the liquid dropletinto contact with the objects.
 3. The method for connecting two objectselectrically according to claim 1, wherein a wiring which communicateswith one of openings of the through hole is formed as one of theobjects, on the first surface of the substrate, at the time of arrangingthe objects.
 4. The method for connecting two objects electricallyaccording to claim 3, wherein upon forming the through hole in thesubstrate, a projection which projects inwardly from an inner wall ofthe through hole is also formed together with the through hole; and thewiring is formed such that the wiring covers a surface of the projectionupon arranging the objects.
 5. The method for connecting two objectselectrically according to claim 3, wherein a liquid repellent propertyof a surface of the wire is lower than a liquid repellent property of asurface of the substrate, at an area different from another area atwhich the wiring is formed.
 6. The method for connecting two objectselectrically according to claim 1, wherein the channel is formed insidethe substrate.
 7. The method for connecting two objects electricallyaccording to claim 1, wherein the channel is a groove formed on thefirst surfaces of the substrate.
 8. The method for connecting twoobjects electrically according to claim 7, wherein a liquid repellentproperty of the first surface of the substrate is higher than a liquidrepellent property of an inner surface of the liquid-receiving portionand a liquid repellent property of the groove.
 9. The method forconnecting two objects electrically according to claim 8, furthercomprising forming a liquid repellent film having a liquid repellentproperty higher than the liquid repellent property of the inner surfaceof the liquid-receiving portion and the liquid repellent property of thegroove, on the first surface of the substrate, before forming thechannel.
 10. The method for connecting two objects electricallyaccording to claim 1, wherein one of the two objects is arranged to beaway from the substrate upon arranging the two objects.